package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;


    @Resource
    private RedissonClient redissonClient;


    private IVoucherOrderService proxy;

    // 创建lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    //创建一个线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    public void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    //用于线程池处理业务
    // 初始化完毕后，就会从队列中获取订单信息，然后进行下单操作
    private class VoucherOrderHandler implements Runnable {
        String queueName = "stream.orders";
        @Override
        public void run() {
            while (true) {
                try {
                    // 1. 获取redis 消息队列中的订单信息 XREADGROUP g1 c1 COUNT 1 BLOCK 1000 STREAMS s1 >
                    List<MapRecord<String, Object, Object>> read = stringRedisTemplate
                            .opsForStream()
                            .read(Consumer.from("g1", "c1"),
                                    StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                                    StreamOffset.create(queueName, ReadOffset.lastConsumed()));
                    //  2.判断消息是否获取成功
                    if (read == null || read.isEmpty()) {
                        continue;
                    }
                    // 3.解析消息中的订单数据 并创建订单
                    RecordId recordId = parseAndCreateOrder(read.get(0));
                    //  5.确认消息消费成功
                    stringRedisTemplate.opsForStream().acknowledge("s1", "g1", recordId);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    //处理异常消息
                    handlePendingList();
                }
            }
        }


    }

    /**
     * 处理pending-list中的消息
     */
    private void handlePendingList() {
        try {
            while (true) {
                List<MapRecord<String, Object, Object>> list = stringRedisTemplate
                        .opsForStream()
                        .read(Consumer.from("g1", "c1"),
                                StreamReadOptions.empty().count(1),
                                StreamOffset.create("stream:orders", ReadOffset.from("0")));

                // 2.判断订单信息是否为空
                if (list == null || list.isEmpty()) {
                    // 如果为null，说明没有异常消息，结束循环
                    break;
                }
                // 解析数据
                MapRecord<String, Object, Object> record = list.get(0);
                // 3.解析消息中的订单数据 并创建订单
                RecordId recordId = parseAndCreateOrder(record);
                // 4.确认消息 XACK
                stringRedisTemplate.opsForStream().acknowledge("s1", "g1", record.getId());
            }
        } catch (Exception e) {
            log.error("处理pending-list异常", e);
            try {
                Thread.sleep(20);
            } catch (Exception e1) {
                log.error("处理订单异常", e1);
            }
        }
    }

    /**
     * 从消息记录中解析订单并创建订单
     *
     * @param record 消息记录
     */
    private RecordId parseAndCreateOrder(MapRecord<String, Object, Object> record) {
        Map<Object, Object> value = record.getValue();
        VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
        proxy.createVoucherOrder(voucherOrder);
        return record.getId();
    }

    /**
     * 处理订单
     *
     * @param voucherOrder 订单信息
     */
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //  1.获取用户
        Long userId = voucherOrder.getUserId();
        // 2.创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        if (!lock.tryLock()) {
            log.error("不允许重复下单");
            return;
        }
        try {
            // 3.获取代理对象
            proxy.createVoucherOrder(voucherOrder);
        } catch (Exception e) {
            log.error("处理订单异常", e);
        } finally {
            lock.unlock();
        }
    }

    /**
     * 秒杀优惠券
     *
     * @param voucherId 优惠券id
     * @return 优惠券id
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.执行lua脚本
        Long userId = UserHolder.getUser().getId();
        long orderId = redisIdWorker.nextId("order");
        Long execute = stringRedisTemplate.execute(SECKILL_SCRIPT, Collections.emptyList(), voucherId.toString(), userId.toString(), String.valueOf(orderId));
        // 2.获取结果
        int r = execute.intValue();
        if (r != 0) {
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 3.获取订单id
        return Result.ok(orderId);
    }

    /**
     * 创建订单
     *
     * @param voucherOrder 优惠券id
     */
    @Override
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getId();
        // 5.1  查询该用户是否已经下过单
        Integer count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        // 5.2  判断结果
        if (count > 0) {
            log.error("用户已经购买过一次了");
        }
        // 6.扣减库存
        boolean success = seckillVoucherService.update()
                //set  stock = stock - 1
                .setSql("stock = stock - 1")
                // where voucher_id = ?
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();
        if (!success) {
            log.error("库存不足");
        }
        save(voucherOrder);
    }
}
